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  <div class="section" id="module-xml.sax">
<span id="xml-sax-support-for-sax2-parsers"></span><h1>20.9. <a class="reference internal" href="#module-xml.sax" title="xml.sax: Package containing SAX2 base classes and convenience functions."><code class="xref py py-mod docutils literal notranslate"><span class="pre">xml.sax</span></code></a> --- Support for SAX2 parsers<a class="headerlink" href="#module-xml.sax" title="永久链接至标题">¶</a></h1>
<p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.6/Lib/xml/sax/__init__.py">Lib/xml/sax/__init__.py</a></p>
<hr class="docutils" />
<p>The <a class="reference internal" href="#module-xml.sax" title="xml.sax: Package containing SAX2 base classes and convenience functions."><code class="xref py py-mod docutils literal notranslate"><span class="pre">xml.sax</span></code></a> package provides a number of modules which implement the
Simple API for XML (SAX) interface for Python.  The package itself provides the
SAX exceptions and the convenience functions which will be most used by users of
the SAX API.</p>
<div class="admonition warning">
<p class="first admonition-title">警告</p>
<p class="last">The <a class="reference internal" href="#module-xml.sax" title="xml.sax: Package containing SAX2 base classes and convenience functions."><code class="xref py py-mod docutils literal notranslate"><span class="pre">xml.sax</span></code></a> module is not secure against maliciously
constructed data.  If you need to parse untrusted or unauthenticated data see
<a class="reference internal" href="xml.html#xml-vulnerabilities"><span class="std std-ref">XML vulnerabilities</span></a>.</p>
</div>
<p>The convenience functions are:</p>
<dl class="function">
<dt id="xml.sax.make_parser">
<code class="descclassname">xml.sax.</code><code class="descname">make_parser</code><span class="sig-paren">(</span><em>parser_list=[]</em><span class="sig-paren">)</span><a class="headerlink" href="#xml.sax.make_parser" title="永久链接至目标">¶</a></dt>
<dd><p>Create and return a SAX <a class="reference internal" href="xml.sax.reader.html#xml.sax.xmlreader.XMLReader" title="xml.sax.xmlreader.XMLReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">XMLReader</span></code></a> object.  The
first parser found will
be used.  If <em>parser_list</em> is provided, it must be a sequence of strings which
name modules that have a function named <code class="xref py py-func docutils literal notranslate"><span class="pre">create_parser()</span></code>.  Modules listed
in <em>parser_list</em> will be used before modules in the default list of parsers.</p>
</dd></dl>

<dl class="function">
<dt id="xml.sax.parse">
<code class="descclassname">xml.sax.</code><code class="descname">parse</code><span class="sig-paren">(</span><em>filename_or_stream</em>, <em>handler</em>, <em>error_handler=handler.ErrorHandler()</em><span class="sig-paren">)</span><a class="headerlink" href="#xml.sax.parse" title="永久链接至目标">¶</a></dt>
<dd><p>Create a SAX parser and use it to parse a document.  The document, passed in as
<em>filename_or_stream</em>, can be a filename or a file object.  The <em>handler</em>
parameter needs to be a SAX <a class="reference internal" href="xml.sax.handler.html#xml.sax.handler.ContentHandler" title="xml.sax.handler.ContentHandler"><code class="xref py py-class docutils literal notranslate"><span class="pre">ContentHandler</span></code></a> instance.  If
<em>error_handler</em> is given, it must be a SAX <a class="reference internal" href="xml.sax.handler.html#xml.sax.handler.ErrorHandler" title="xml.sax.handler.ErrorHandler"><code class="xref py py-class docutils literal notranslate"><span class="pre">ErrorHandler</span></code></a>
instance; if
omitted,  <a class="reference internal" href="#xml.sax.SAXParseException" title="xml.sax.SAXParseException"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SAXParseException</span></code></a> will be raised on all errors.  There is no
return value; all work must be done by the <em>handler</em> passed in.</p>
</dd></dl>

<dl class="function">
<dt id="xml.sax.parseString">
<code class="descclassname">xml.sax.</code><code class="descname">parseString</code><span class="sig-paren">(</span><em>string</em>, <em>handler</em>, <em>error_handler=handler.ErrorHandler()</em><span class="sig-paren">)</span><a class="headerlink" href="#xml.sax.parseString" title="永久链接至目标">¶</a></dt>
<dd><p>Similar to <a class="reference internal" href="#xml.sax.parse" title="xml.sax.parse"><code class="xref py py-func docutils literal notranslate"><span class="pre">parse()</span></code></a>, but parses from a buffer <em>string</em> received as a
parameter.  <em>string</em> must be a <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> instance or a
<a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a>.</p>
<div class="versionchanged">
<p><span class="versionmodified">在 3.5 版更改: </span>Added support of <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> instances.</p>
</div>
</dd></dl>

<p>A typical SAX application uses three kinds of objects: readers, handlers and
input sources.  &quot;Reader&quot; in this context is another term for parser, i.e. some
piece of code that reads the bytes or characters from the input source, and
produces a sequence of events. The events then get distributed to the handler
objects, i.e. the reader invokes a method on the handler.  A SAX application
must therefore obtain a reader object, create or open the input sources, create
the handlers, and connect these objects all together.  As the final step of
preparation, the reader is called to parse the input. During parsing, methods on
the handler objects are called based on structural and syntactic events from the
input data.</p>
<p>For these objects, only the interfaces are relevant; they are normally not
instantiated by the application itself.  Since Python does not have an explicit
notion of interface, they are formally introduced as classes, but applications
may use implementations which do not inherit from the provided classes.  The
<a class="reference internal" href="xml.sax.reader.html#xml.sax.xmlreader.InputSource" title="xml.sax.xmlreader.InputSource"><code class="xref py py-class docutils literal notranslate"><span class="pre">InputSource</span></code></a>, <a class="reference internal" href="xml.sax.reader.html#xml.sax.xmlreader.Locator" title="xml.sax.xmlreader.Locator"><code class="xref py py-class docutils literal notranslate"><span class="pre">Locator</span></code></a>,
<code class="xref py py-class docutils literal notranslate"><span class="pre">Attributes</span></code>, <code class="xref py py-class docutils literal notranslate"><span class="pre">AttributesNS</span></code>,
and <a class="reference internal" href="xml.sax.reader.html#xml.sax.xmlreader.XMLReader" title="xml.sax.xmlreader.XMLReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">XMLReader</span></code></a> interfaces are defined in the
module <a class="reference internal" href="xml.sax.reader.html#module-xml.sax.xmlreader" title="xml.sax.xmlreader: Interface which SAX-compliant XML parsers must implement."><code class="xref py py-mod docutils literal notranslate"><span class="pre">xml.sax.xmlreader</span></code></a>.  The handler interfaces are defined in
<a class="reference internal" href="xml.sax.handler.html#module-xml.sax.handler" title="xml.sax.handler: Base classes for SAX event handlers."><code class="xref py py-mod docutils literal notranslate"><span class="pre">xml.sax.handler</span></code></a>.  For convenience,
<a class="reference internal" href="xml.sax.reader.html#xml.sax.xmlreader.InputSource" title="xml.sax.xmlreader.InputSource"><code class="xref py py-class docutils literal notranslate"><span class="pre">InputSource</span></code></a> (which is often
instantiated directly) and the handler classes are also available from
<a class="reference internal" href="#module-xml.sax" title="xml.sax: Package containing SAX2 base classes and convenience functions."><code class="xref py py-mod docutils literal notranslate"><span class="pre">xml.sax</span></code></a>.  These interfaces are described below.</p>
<p>In addition to these classes, <a class="reference internal" href="#module-xml.sax" title="xml.sax: Package containing SAX2 base classes and convenience functions."><code class="xref py py-mod docutils literal notranslate"><span class="pre">xml.sax</span></code></a> provides the following exception
classes.</p>
<dl class="exception">
<dt id="xml.sax.SAXException">
<em class="property">exception </em><code class="descclassname">xml.sax.</code><code class="descname">SAXException</code><span class="sig-paren">(</span><em>msg</em>, <em>exception=None</em><span class="sig-paren">)</span><a class="headerlink" href="#xml.sax.SAXException" title="永久链接至目标">¶</a></dt>
<dd><p>Encapsulate an XML error or warning.  This class can contain basic error or
warning information from either the XML parser or the application: it can be
subclassed to provide additional functionality or to add localization.  Note
that although the handlers defined in the
<a class="reference internal" href="xml.sax.handler.html#xml.sax.handler.ErrorHandler" title="xml.sax.handler.ErrorHandler"><code class="xref py py-class docutils literal notranslate"><span class="pre">ErrorHandler</span></code></a> interface
receive instances of this exception, it is not required to actually raise the
exception --- it is also useful as a container for information.</p>
<p>When instantiated, <em>msg</em> should be a human-readable description of the error.
The optional <em>exception</em> parameter, if given, should be <code class="docutils literal notranslate"><span class="pre">None</span></code> or an exception
that was caught by the parsing code and is being passed along as information.</p>
<p>This is the base class for the other SAX exception classes.</p>
</dd></dl>

<dl class="exception">
<dt id="xml.sax.SAXParseException">
<em class="property">exception </em><code class="descclassname">xml.sax.</code><code class="descname">SAXParseException</code><span class="sig-paren">(</span><em>msg</em>, <em>exception</em>, <em>locator</em><span class="sig-paren">)</span><a class="headerlink" href="#xml.sax.SAXParseException" title="永久链接至目标">¶</a></dt>
<dd><p>Subclass of <a class="reference internal" href="#xml.sax.SAXException" title="xml.sax.SAXException"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SAXException</span></code></a> raised on parse errors. Instances of this
class are passed to the methods of the SAX
<a class="reference internal" href="xml.sax.handler.html#xml.sax.handler.ErrorHandler" title="xml.sax.handler.ErrorHandler"><code class="xref py py-class docutils literal notranslate"><span class="pre">ErrorHandler</span></code></a> interface to provide information
about the parse error.  This class supports the SAX
<a class="reference internal" href="xml.sax.reader.html#xml.sax.xmlreader.Locator" title="xml.sax.xmlreader.Locator"><code class="xref py py-class docutils literal notranslate"><span class="pre">Locator</span></code></a> interface as well as the
<a class="reference internal" href="#xml.sax.SAXException" title="xml.sax.SAXException"><code class="xref py py-class docutils literal notranslate"><span class="pre">SAXException</span></code></a> interface.</p>
</dd></dl>

<dl class="exception">
<dt id="xml.sax.SAXNotRecognizedException">
<em class="property">exception </em><code class="descclassname">xml.sax.</code><code class="descname">SAXNotRecognizedException</code><span class="sig-paren">(</span><em>msg</em>, <em>exception=None</em><span class="sig-paren">)</span><a class="headerlink" href="#xml.sax.SAXNotRecognizedException" title="永久链接至目标">¶</a></dt>
<dd><p>Subclass of <a class="reference internal" href="#xml.sax.SAXException" title="xml.sax.SAXException"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SAXException</span></code></a> raised when a SAX
<a class="reference internal" href="xml.sax.reader.html#xml.sax.xmlreader.XMLReader" title="xml.sax.xmlreader.XMLReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">XMLReader</span></code></a> is
confronted with an unrecognized feature or property.  SAX applications and
extensions may use this class for similar purposes.</p>
</dd></dl>

<dl class="exception">
<dt id="xml.sax.SAXNotSupportedException">
<em class="property">exception </em><code class="descclassname">xml.sax.</code><code class="descname">SAXNotSupportedException</code><span class="sig-paren">(</span><em>msg</em>, <em>exception=None</em><span class="sig-paren">)</span><a class="headerlink" href="#xml.sax.SAXNotSupportedException" title="永久链接至目标">¶</a></dt>
<dd><p>Subclass of <a class="reference internal" href="#xml.sax.SAXException" title="xml.sax.SAXException"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SAXException</span></code></a> raised when a SAX
<a class="reference internal" href="xml.sax.reader.html#xml.sax.xmlreader.XMLReader" title="xml.sax.xmlreader.XMLReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">XMLReader</span></code></a> is asked to
enable a feature that is not supported, or to set a property to a value that the
implementation does not support.  SAX applications and extensions may use this
class for similar purposes.</p>
</dd></dl>

<div class="admonition seealso">
<p class="first admonition-title">参见</p>
<dl class="last docutils">
<dt><a class="reference external" href="http://www.saxproject.org/">SAX: The Simple API for XML</a></dt>
<dd>This site is the focal point for the definition of the SAX API.  It provides a
Java implementation and online documentation.  Links to implementations and
historical information are also available.</dd>
<dt>Module <a class="reference internal" href="xml.sax.handler.html#module-xml.sax.handler" title="xml.sax.handler: Base classes for SAX event handlers."><code class="xref py py-mod docutils literal notranslate"><span class="pre">xml.sax.handler</span></code></a></dt>
<dd>Definitions of the interfaces for application-provided objects.</dd>
<dt>Module <a class="reference internal" href="xml.sax.utils.html#module-xml.sax.saxutils" title="xml.sax.saxutils: Convenience functions and classes for use with SAX."><code class="xref py py-mod docutils literal notranslate"><span class="pre">xml.sax.saxutils</span></code></a></dt>
<dd>Convenience functions for use in SAX applications.</dd>
<dt>Module <a class="reference internal" href="xml.sax.reader.html#module-xml.sax.xmlreader" title="xml.sax.xmlreader: Interface which SAX-compliant XML parsers must implement."><code class="xref py py-mod docutils literal notranslate"><span class="pre">xml.sax.xmlreader</span></code></a></dt>
<dd>Definitions of the interfaces for parser-provided objects.</dd>
</dl>
</div>
<div class="section" id="saxexception-objects">
<span id="sax-exception-objects"></span><h2>20.9.1. SAXException Objects<a class="headerlink" href="#saxexception-objects" title="永久链接至标题">¶</a></h2>
<p>The <a class="reference internal" href="#xml.sax.SAXException" title="xml.sax.SAXException"><code class="xref py py-class docutils literal notranslate"><span class="pre">SAXException</span></code></a> exception class supports the following methods:</p>
<dl class="method">
<dt id="xml.sax.SAXException.getMessage">
<code class="descclassname">SAXException.</code><code class="descname">getMessage</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xml.sax.SAXException.getMessage" title="永久链接至目标">¶</a></dt>
<dd><p>Return a human-readable message describing the error condition.</p>
</dd></dl>

<dl class="method">
<dt id="xml.sax.SAXException.getException">
<code class="descclassname">SAXException.</code><code class="descname">getException</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xml.sax.SAXException.getException" title="永久链接至目标">¶</a></dt>
<dd><p>Return an encapsulated exception object, or <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p>
</dd></dl>

</div>
</div>


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